como usar o ary no javascript es6

Creates a function that accepts up to n arguments, ignoring any additional arguments.

Call the provided function, fn, with up to n arguments, using Array.prototype.slice(0, n) and the spread operator (...).

const ary = (fn, n) => (...args) => fn(...args.slice(0, n));

const firstTwoMax = ary(Math.max, 2);
[[2, 6, 'a'], [6, 4, 8], [10]].map(x => firstTwoMax(...x)); // [6, 6, 10]

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